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Question:

Can you put a blow off valve/dump valve on a diesel e46 BMW 320d?

Hi i have a 00 bmw 320d and am trying to find out information on puting a dump valve in, is it possible?, what type of dump valve? and how hard it would be to put in?? any help would be much appreciated.....Thanks!!

Answer:

Most diesels do not have throttle valves (including yours), therefore a blow off valve would never work. They work by relieving the pressure build up caused when the throttle valve is closed (foot lifted off gas pedal in a petrol engine), which happens when you shift (usually only for manuals) so the built up pressure does not bring the turbo speed down. A side effect of this pressure being dumped is the whoosh sound, which some people desire more than the performance gains it offers. That sound is the air rushing out of the intake system, which usually has been metered already, and now is wasted. The ECU measures that air and adds fuel for it. When it gets blown to atmosphere, the fuel is added, but not the air. Now the engine is running rich. There are some systems that recirc that air back to the turbo, but then there is no whoosh sound. Anyway, since most diesels do not even have a throttle valve, it won't do any good.
Dump Valve Diesel

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